2.8 - Addons Window is blank!
There are two options that you could try. 



The Factory Startup

The first would be to start Blender from command line with the --factory-startup which should prevent the broken add-on to be activated on startup.


Open the Windows Explorer Win+E
Navigate to the installation directory of Blender 2.8. You should see the blender.exe in the folder.
Type cmd in the path field and press enter. The command line prompt should open.
Type .\blender.exe --factory-startup on the command line and press enter


Blender should now start with the factory settings and you should be able to open the add-ons section of the preferences. Find the broken add-on in the list, open the detail section and click on the Remove button.



Manually Removing an Add-on

You should only use this approach if the first one didn't work, either because the add-ons are still not listed or there is no remove button for the add-on. If the former occurred, please report this on Blender's bug tracker (Help > Report a Bug). The latter will happen if you manually copied the add-on files to the add-ons directory instead of installing it through the UI. 

If you know what files have been installed with the add-on you can remove them manually. Do not remove any files if you're not 100% certain that they are part of the problematic add-on. The add-on should be installed in one of the following subfolders in Blender's installation directory: 


\2.80\scripts\addons
\2.80\scripts\addons_contrib


You can simply delete the broken add-on files and it should be working again.